refactor: 删除compose_video中legacy渲染引擎分支，统一走unified

apps/worker/worker_app/tasks/compose_video.py

@@ -1,6 +1,6 @@
 """视频合成 Celery 任务 — Phase 8 任务 2.10.
 
-使用 JobService 管理任务生命周期，集成 VideoComposeService 执行合成。
+使用 JobService 管理任务生命周期，通过 RenderAdapter 调用 UnifiedRenderService 执行合成。
 """
 
 from __future__ import annotations
@@ -35,9 +35,7 @@ def _get_job_service():
 def compose_video(self, job_id: str, **kwargs):
     """视频合成任务。
 
-    根据 RENDER_ENGINE 配置选择渲染引擎：
-      - legacy: 旧 VideoComposeService（filter_complex 模式）
-      - unified: 新 UnifiedRenderService（图层架构）
+    使用 UnifiedRenderService（图层架构）进行渲染。
 
     Args:
         job_id: JobService 中的任务 ID
@@ -56,30 +54,8 @@ def compose_video(self, job_id: str, **kwargs):
             job_service.fail_job(job_id, "Missing plan_id in job payload")
             return {"status": "error", "message": "Missing plan_id"}
 
-        # 判断使用哪个渲染引擎
-        # 优先级：Redis Feature Flag（白名单 > 百分比） > 环境变量默认
-        from video_processing.render_engine_resolver import get_render_engine_resolver
-
-        resolver = get_render_engine_resolver()
-        user_id = job.created_by_user_id or None
-        engine = resolver.get_engine(user_id=user_id)
-        # 灰度期间打印详细 flag 配置，便于排查
-        config = resolver.get_config_snapshot()
-        logger.info(
-            "compose_video 引擎选择: job_id=%s engine=%s user_id=%s enabled=%s percentage=%s whitelist=%d default=%s",
-            job_id,
-            engine,
-            user_id,
-            config.get("enabled"),
-            config.get("percentage"),
-            len(config.get("whitelist", [])),
-            config.get("default_engine"),
-        )
-
-        if engine == "unified":
-            return _compose_with_unified_engine(self, job_service, job, plan_id, db)
-        else:
-            return _compose_with_legacy_engine(self, job_service, job, plan_id, db)
+        # 使用 unified 渲染引擎
+        return _compose_with_unified_engine(self, job_service, job, plan_id, db)
 
     except self.retry_exc as exc:
         logger.warning("视频合成重试中: job_id=%s, exc=%s", job_id, exc)
@@ -95,69 +71,6 @@ def compose_video(self, job_id: str, **kwargs):
         db.close()
 
 
-def _compose_with_legacy_engine(task, job_service, job, plan_id: str, db) -> dict:
-    """旧引擎渲染路径（VideoComposeService）。"""
-    job_id = job.id
-
-    # 标记为 running
-    job_service.update_progress(job_id, progress=10.0, current_stage="初始化合成环境")
-
-    # 延迟导入 VideoComposeService
-    from apps.api.app.services.video_compose_service import VideoComposeService
-
-    compose_svc = VideoComposeService(db)
-
-    # 校验合成条件
-    job_service.update_progress(job_id, progress=20.0, current_stage="校验合成条件")
-    validation = compose_svc.validate_compose(plan_id)
-    if not validation.valid:
-        error_msg = "; ".join(validation.errors)
-        job_service.fail_job(job_id, f"合成校验失败: {error_msg}")
-        return {"status": "error", "message": error_msg}
-
-    # 构建合成命令
-    job_service.update_progress(job_id, progress=30.0, current_stage="构建 FFmpeg 命令")
-    _output_dir = os.environ.get("VIDEO_OUTPUT_DIR", os.path.join(tempfile.gettempdir(), "video_output"))
-    output_path = os.path.join(_output_dir, f"{job_id}.mp4")
-    compose_cmd = compose_svc.build_compose_command(plan_id, output_path)
-
-    # 执行 FFmpeg
-    job_service.update_progress(job_id, progress=50.0, current_stage="正在执行视频合成")
-    logger.info("Executing FFmpeg for job %s, plan %s", job_id, plan_id)
-
-    try:
-        from video_processing.ffmpeg_utils import run_ffmpeg
-
-        run_ffmpeg(compose_cmd.command, timeout=3600)
-    except Exception as e:
-        error_msg = f"FFmpeg 执行失败: {str(e)[:500]}"
-        job_service.fail_job(job_id, error_msg)
-        raise
-
-    # 上传结果
-    job_service.update_progress(job_id, progress=80.0, current_stage="上传合成结果")
-    storage_key = f"rendered/{plan_id}/{job_id}.mp4"
-
-    from worker_app.tasks.edit_plan_generation import _upload_to_oss
-
-    output_url = _upload_to_oss(Path(output_path), storage_key)
-
-    # 更新 Job 状态为完成
-    result_data = {
-        "plan_id": plan_id,
-        "output_path": output_path,
-        "storage_key": storage_key,
-        "output_url": output_url or "",
-        "estimated_duration": compose_cmd.estimated_duration,
-        "clip_count": len(compose_cmd.clip_chains),
-        "engine": "legacy",
-    }
-    job_service.complete_job(job_id, result=result_data)
-
-    logger.info("视频合成完成(legacy): job_id=%s, plan_id=%s", job_id, plan_id)
-    return {"status": "completed", "job_id": job_id, "result": result_data}
-
-
 def _compose_with_unified_engine(task, job_service, job, plan_id: str, db) -> dict:
     """新引擎渲染路径（UnifiedRenderService + RenderAdapter）。"""
     job_id = job.id